Case Study of an East Siberian Field: A Holistic Review of Drilling Performance Enhancement

Abstract

The Verkhnechonskoye (VCNG) oilfield located in Eastern Siberia is developed on pad clusters, with in excess of 200 wells drilled to date. Typical well geometry consists of a vertical 13 3/8in. conductor followed by directional 12 ¼ in. and 8 ½ in. sections ran with subsequent 9 5/8in. and 7in. casing strings. Production hole is drilled in 6in. with a 4 ½in. liner set prior to completion. The predominant well design incorporates a double build profile which lands horizontally in the Verknechonskiy reservoir with an approximate 600m lateral drilled in the productive zone. VCNG field has evolved of key strategic importance to deliver oil through the Eastern Siberia Pacific Ocean (ESPO) pipeline from Russia to the vast Asia-Pacific market located to its South East. Increasing production targets have been required to deliver hydrocarbons to fulfill aggressive pipeline commitments. Meeting these requirements have in turn initiated a relentless drive to enhance operational efficiency since the inception of development drilling phase in 2007; leading to a significant increase in drilling performance and reduction in overall well construction time in the period to date. This improvement has been achieved against the backdrop of an environment which is extremely challenging on several distinct fronts; remoteness of the project with >600km from the nearest major conurbation, harshness of an extreme continental climate with temperatures seasonally dropping to -50°C and coupled with a unique and problematic lithological column all serve to make drilling, logistics and general operations a complex undertaking. The purpose of this paper will be to take a holistic review of drilling performance in the field and to chronicle the numerous incremental technological and procedural advancements which have led to a reduction in average well construction time from 58 to 21 days between 2007 and 2011. Incorporated into this dramatic efficiency improvement includes a 465% increase in average well ROP along with a corresponding increase in meters drilled per circulating hour (MPCH) of 390%.